const user = {
  name: "hdcms",
  age: 12
};
Object.preventExtensions(user);
console.log(JSON.stringify(Object.getOwnPropertyDescriptors(user), null, 2));
if (Object.isExtensible(user)) {
  user.site = "houdunren.com";
  console.log(user);
}
// delete user.name;
user.name = "后擀人";
console.log(user);
// for (const [key, value] of Object.entries(user)) {
//   console.log(key, value);
// }
